The primary objective of this research is to study the action of two classes of addicting drugs, barbiturates and opiates, on electrical brain activity, especially contingent negative variation (CNV), and psycho-physiological functioning in humans. A secondary objective is to further study the properties of CNV, which is an accurate indicator of alteration in brain function and correlates with behavioral states of arousal and correlates with behavioral states of arousal and attention. In addition to CNV measures, patterns of arousal will be observed, mood, heart rate, vertical eye movement and muscle tension will be measured, the Minnesota Multiphasic Personality Inventory will be administered and a post-experimental interview will be conducted. Three studies will be conducted. The first study will investigate the action of fast and slow acting barbiturates on normals. The second will investigate the effects of fast and slow acting barbiturate ingestion in barbiturate addicts during withdrawal from barbiturates. In addition, these barbiturate addicts will be differentiated on the basis of observed agitation. The third study will investigate the action of a stabilization dose of an opiate, methadone, and the effects of ingestion of methadone during such stabilization. Subjects addicted to methadone will additionally be differentiated on the basis of observed patterns of agitation.